Spiral Stainless Steel Coil Tube — Coiltube Product Specification

1. Product Overview

The Spiral Stainless Steel Coil Tube (hereinafter referred to as "Coiltube") is a continuously formed tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. This product is engineered for high-performance heat exchange applications, particularly in spiral coil heat transfer furnaces (螺旋盘管式导热炉) where efficient thermal management and combustion optimization are critical. The Coiltube is produced through a continuous coil-forming process that yields a geometrically consistent, spring-like helical configuration with uniform cross-sectional properties throughout its entire length.

Based on extensive numerical simulation research into heat transfer and combustion characteristics of spiral coil heat transfer furnaces, the Coiltube design leverages the inherent advantages of helical geometry — including enhanced turbulence promotion, increased surface-to-volume ratio, and superior convective heat transfer coefficients — to deliver exceptional thermal efficiency in industrial heating and energy conversion systems.

2. Material & Properties

2.1 Base Alloy Grades

The Coiltube is manufactured from austenitic and duplex stainless steel grades selected for their outstanding corrosion resistance, mechanical integrity at elevated temperatures, and long-term durability under thermal cycling conditions:

2.2 Key Material Properties

Property SAE 304 SAE 316 SAE 310S
Chromium (Cr) 18.0–20.0 % 16.0–18.0 % 24.0–26.0 %
Nickel (Ni) 8.0–10.5 % 10.0–14.0 % 19.0–22.0 %
Molybdenum (Mo) — 2.0–3.0 % —
Carbon (C) ≤ 0.08 % ≤ 0.08 % ≤ 0.08 %
Tensile Strength ≥ 515 MPa ≥ 515 MPa ≥ 205 MPa
Yield Strength (0.2% offset) ≥ 205 MPa ≥ 205 MPa ≥ 103 MPa
Maximum Service Temperature 870 °C 870 °C 1150 °C
Thermal Conductivity (at 100 °C) 16.3 W/(m·K) 16.3 W/(m·K) 18.0 W/(m·K)
Coefficient of Thermal Expansion (20–100 °C) 17.3 × 10⁻⁶ /K 17.3 × 10⁻⁶ /K 18.0 × 10⁻⁶ /K

2.3 Surface Finish Options

3. Specifications

Parameter Specification Range
Outer Diameter (OD) 6 mm – 108 mm (customizable)
Wall Thickness 0.5 mm – 6.0 mm
Coil Pitch (Helical Pitch) 15 mm – 150 mm
Coil Diameter (Mean Diameter) 50 mm – 500 mm
Coil Length (Total Developed Length) Up to 500 m per coil (continuous forming)
Number of Turns Configurable based on application requirements
End Condition Plain end, flared end, or threaded end
Applicable Standards ASTM A269, ASTM A213, ASME B36.19M, EN 10216-5, GB/T 12770
Heat Treatment Annealed and pickled (solution annealed at 1050–1100 °C followed by rapid cooling)
Test Pressure Hydrostatic test at 1.5× design pressure per ASTM A269

4. Manufacturing Process

4.1 Process Flow

  1. Raw Material Selection & Inspection — Incoming stainless steel flat strip or seamless tube stock is verified against chemical composition requirements (via Optical Emission Spectrometry, OES) and mechanical property specifications.
  2. Surface Preparation — De-oiling, descaling, and pickling of the base material to ensure a clean, oxide-free surface suitable for forming.
  3. Continuous Coil Forming (Roll Forming) — The flat strip or pre-formed tube blank passes through a series of precisely calibrated progressive rolls that incrementally bend the material into the desired helical geometry. This process maintains dimensional accuracy and avoids material thinning or work hardening at critical stress points.
  4. In-Line Heat Treatment (if required) — For high-temperature grades, a continuous annealing furnace may be integrated into the production line to relieve residual stresses and restore full annealed mechanical properties.
  5. Pickling & Passivation — Post-forming chemical treatment to remove any scale formed during heat treatment and to establish a robust passive chromium oxide film (Cr₂O₃) for corrosion protection.
  6. Dimensional Inspection & Quality Control — Each coil undergoes verification of outer diameter, wall thickness, pitch accuracy, and total length using laser micrometers, ultrasonic thickness gauges, and coordinate measuring systems.
  7. Hydrostatic Pressure Testing — Every coil is subjected to hydrostatic pressure testing at 1.5 times the maximum design working pressure to verify structural integrity and weld/joint soundness.
  8. Final Inspection, Packaging & Dispatch — Coils are wound onto protective spools, wrapped with moisture-barrier packaging, and shipped with complete mill test certificates (MTC) and material traceability documentation.

4.2 Numerical Simulation-Driven Design Optimization

Wenzhou Jixing Metal Materials Co., Ltd. incorporates findings from advanced numerical simulation research — specifically Computational Fluid Dynamics (CFD) modeling of heat transfer and combustion characteristics in spiral coil heat transfer furnaces — into the design and optimization of their Coiltube products. Key simulation-derived design parameters include:

5. Applications

5.1 Primary Application Domains

5.2 Performance Advantages in Heat Transfer Furnaces

The helical geometry of the Coiltube generates Dean vortices — secondary rotational flows perpendicular to the primary axial flow — which significantly enhance radial mixing and increase the convective heat transfer coefficient by 20–40% compared to equivalent straight-tube configurations. This phenomenon, validated through numerical simulation studies, translates directly into higher thermal efficiency, reduced furnace footprint, and lower fuel consumption in spiral coil heat transfer furnace applications.

6. Quality Certifications & Compliance

6.1 Applicable Standards

6.2 Quality Assurance Measures

6.3 Certifications & Accreditations

7. Unique Selling Points

8. Ordering Information

Customers are advised to specify the following parameters when placing orders: